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Public water system record

City of Hollister

Serves Hollister, San Benito County, CA · 26,017 people served

Federal records show 3 health-based violations and 2 monitoring/reporting issues for City of Hollister in the last ten years. The most serious issue in this window was a resolved Total Trihalomethanes (TTHMs) violation.

  • CA3510001
  • HOLLISTER
  • CA
  • 26,017 served

System profile

Source water Purchased surface water
ZIP 95023
EPA system ID CA3510001

Verify this system on EPA ECHO →

Health-based violations, last 10 years
3
Resolved
3
Unresolved
0
Any acute record
No
Monitoring issues, last 10 years
2

Key facts

  • City of Hollister draws water from 5 wells.
  • Highest measured level in the last 10 years: Total Trihalomethanes (TTHMs), 0.092 mg/L, federal limit 0.08 mg/L (1.2 times the limit), 2018.
  • Most recent formal enforcement: compliance order (no penalty) by California, July 2024.
  • Record on file since 1987, with 3 health-based violations before October 19, 2016.
  • Lead pipe inventory: 0 lead and 0 unknown out of 7,597 service lines.

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Health-based violations

Since October 2016

Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.

Contaminant Rule family Start date Status Acute
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.086 mg/L, federal limit 0.08 mg/L (1.1 times the limit)
 220 Jul 1, 2022 Resolved No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 220 Oct 1, 2018 Resolved No
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.092 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
 220 Jul 1, 2018 Resolved No

Monitoring and reporting issues

Since October 2016

Missed tests or reports, not contaminants found above a limit.

Issue Start date Status
Haloacetic Acids (HAA5)
Monitoring and reporting
 Apr 1, 2024 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.
Total Trihalomethanes (TTHMs)
Monitoring and reporting
 Apr 1, 2024 Archived
Violation period ended. EPA no longer counts it toward current compliance, but no fix was formally recorded.

Full record since 1987

EPA's records for City of Hollister go back to 1987. Before October 19, 2016 they list 3 health-based violations (3 resolved) and 10 monitoring or reporting violations.

Violations that began in Health-based Monitoring and reporting
1980s 0 1
1990s 1 4
2000s 0 2
2010 to October 18, 2016 2 3
October 19, 2016 to 2019 2 0
2020s 1 2

Most recent health-based violation before October 19, 2016: Total Trihalomethanes (TTHMs), began January 2016, Resolved.

Show all 3 health-based violations before October 19, 2016
Contaminant Start date Status
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.082 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 Jan 1, 2016 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.083 mg/L, federal limit 0.08 mg/L (at or just above the limit)
 Oct 1, 2015 Resolved
Nitrate (acute)
Contaminant limit exceeded
 Jan 1, 1999 Resolved

Enforcement actions

California regulators took 7 formal enforcement actions against City of Hollister between 1999 and 2024. The most recent was a compliance order (no penalty) in July 2024.

Date By Action Violations covered
Jul 25, 2024 California Compliance order (no penalty) 2 violations: Total Trihalomethanes (TTHMs), Haloacetic Acids (HAA5)
Oct 10, 2022 California Compliance order (no penalty) 1 violation (1 health-based): Total Trihalomethanes (TTHMs)
Jan 11, 2019 California Compliance order (no penalty) 2 violations (2 health-based): Total Trihalomethanes (TTHMs)
Apr 11, 2016 California Compliance order (no penalty) 2 violations (2 health-based): Total Trihalomethanes (TTHMs)
Aug 31, 2010 California Compliance order (no penalty) 2 violations: Nitrate
May 7, 2002 California Compliance order (no penalty) 2 violations: Nitrate, Benzene
Apr 24, 1999 California Compliance order (no penalty) 1 violation (1 health-based): Nitrate

What the violations mean

Total Trihalomethanes (TTHMs)

3 incidents

Disinfection byproduct levels exceeded the federal limit

Long-term TTHM exposure may increase bladder cancer risk

Where the water comes from

City of Hollister draws water from 5 wells. It also buys water from San Benito County Water District and Sunnyslope County Water Dist. 1 other community water system buys water from City of Hollister. 2 other public water systems have emergency connections to City of Hollister.

Buys water from

Community systems that buy water from it

Annual water quality report

City of Hollister must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.

Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.

Find a posted report with EPA's Consumer Confidence Report search

Testing your own water

To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by California.

Certified drinking water labs by state EPA guidance for private wells